Sound absorbing fireproof cotton is made with natural rock as the main raw material. It is melted at high temperature and centrifugally sprayed to produce a mineral fiber, to which is added a small amount of thermosetting binder before a pendulum method is employed. Its characteristics include non-combustibility, non-toxicity, low thermal conductivity, water immersion, sound absorption, physical and chemical stability, and it can be finished with aluminum foil, glass fiber cloth or other decorative surfaces on top of the rock wool board.